1. Field of the Invention
The invention relates to an apparatus and method for obtaining soil samples, and more particularly, to an apparatus utilizing a release and retrieve mechanism not requiring the repetitive and time consuming assembly and disassembly of sections of a center rod to obtain the soil samples, or for performing other tasks requiring an item to be lowered into a drill bore, released at the bottom of the bore, and then retrieved without assembling and disassembling sections of center rod.
2. Description of the Related Art
In the past, most soil sampling systems were used for geophysical applications (i.e., design and construction, oil and mineral exploration, etc.). These applications do not require stringent levels of integrity for the samples. More recently, soil sampling increasingly has been carried out for the purpose of environmental monitoring. For these applications, integrity of the samples is critical because it is desirable to obtain accurate analyses of small concentrations of contaminants at specific depths. Existing sampling methods are not entirely satisfactory for environmental monitoring purposes because they require the time-consuming assembly and disassembly of a center rod at every depth for which a sample is required.
In using existing soil sampling apparatus, after a well is drilled using a tube auger to a depth at which a sample is desired, a sampling tube must be inserted into the auger. This is accomplished through the use of a center rod. A center rod section adapted for taking samples (i.e., a sampling tube) is inserted first. Next, successive center rod sections, typically having a length of five feet, are added one by one to the top of the previous center rod sections and inserted into the auger. After each successive center rod section has been detachably attached to the top section of center rod in the auger (which can remain in the bore until the drilling is complete to the desired depth), the center rod is lowered farther into the auger and then held while another section is detachably attached to the top end of the previously added section. This process of adding center rod sections is repeated until enough sections have been added so that the sampling tube is at the bottom of the bore. The sample is then taken by pushing the sampling tube into the soil at the bottom of the bore.
After the sample is taken, the sampling tube containing the sample is removed from the bore by raising the entire center rod out of the auger and removing each section, one at a time. Thus, obtaining a soil sample by prior methods is a time-consuming process. When samples are needed from several depths, these difficulties are compounded. Thus, an apparatus for taking soil samples faster and more efficiently is desirable.